1. Field of the Invention
The present invention relates to an antenna, particularly to a miniature multi-frequency antenna, that is suitable for being utilized in small-sized communication devices and is capable of receiving and transmitting multi-frequency signals.
2. The Prior Arts
Nowadays, an antenna plays an important role in various wireless communication electronic devices. With the progress and development of Integrated Circuit (IC) technology, various electronic elements have been miniaturized. Thus, the trend for the development of wireless communication devices is toward light weight, thin profile and compact size while still providing various functions such as data processing, network connection, voice signals transmitting/receiving, audio/video signals broadcasting, etc. Therefore, it is preferred to have a small-sized antenna with the capability of transmitting and receiving multi-frequency signals.
In general, a Planar Inverted F Antenna (PIFA) or a Loop Antenna is a conventional choice to be frequently used in small-sized wireless communication devices. Both are widely utilized due to their simple construction, low cost, easy design, and small size. However, the PIFA is susceptible to the reactance effect of nearby dielectric materials (for example, human body) and results in the resonant frequency deviation of the antenna. Namely, any elements near the antenna might significant influence antennas' characteristics so that the signal transmitting/receiving efficiency of the antenna might be reduced. A Loop Antenna normally shows less susceptibility to its surrounding environment. However, it is usually capable of receiving signals of a single frequency only due to its relatively narrow bandwidth. In order to receive signals with more than two frequencies, a plurality of antennas must be integrated in a wireless communication electronic device that will enlarge the size of the antenna
In view of the problems and shortcomings of the prior art, the present invention provides a miniature multi-frequency antenna for solving aforementioned problems.